Effect of different sources of organic manures on phosphorus availability in vertisol

Abstract

An incubation study was conducted during 2024-2025 with six treatments viz., Absolute control, GRDF (50:75:45 N: P2O5:K2O Kg ha-1 + FYM 10 t ha -1), RD NK+100% RD- P2O5 + PMC 2.0 t ha -1, RD NK+75% RD- P2O5 + PMC 4.0 t ha -1, RD NK +100% RD- P2O5 + PROM 0.5 t ha -1 and RD NK + 75% RD- P2O5 + PROM 1.0 t ha -1 and four replications to study the periodical release of phosphorus at 15 days interval up to 90 days. The result revealed that the application of RD NK+75% RD- P2O5 + PROM 1.0 t ha-1 recorded significantly higher available phosphorus (17.77, 20.03, 25.26, 28.91, 30.12 and 30.51 mg kg-1) over rest of treatments during incubation at 15, 30, 45, 60, 75 and 90 days of incubation, respectively. The organic carbon and soil available potassium was significantly higher (0.54% and 416.20 kg ha-1, respectively) with application of GRDF -50:75:45 N: P2O5:K2O kg ha-1 + FYM 10 t ha -1 at 90 days of incubation period. The soil available phosphorus shows highly significant and positive correlation with OC, available N and K, however it shows a significant negative correlation with CaCO3.